Hydraulic pump or motor



March 16,1937. E. K. BENEDEK 2,@74,20

HYDRAULIC PUMP OR MOTOR Fil 57 t. 16, 1955 4 Sheets-Sheet l i HI I All57 ll 7? mm KEJENEUEK 1 1i. 1., flapgwflyfl March16,].93';7. EKB NEDEK2,0743% HYDRAULIC PUMP OR MOTOR Filed Oct. 16, 1935 4 Sheets-Sheet 2 Varch 16, 193?. E. K/BENEDEK v 2,074,206

HYDRAULIC PUMP OQR'MOTOR v Filed Oct. 16, 1955 4 Sheets-Sheet 3 IEKDENEDEK- Patented Mar. 16, 1937 UNITED STATES PATENT OFFICE 16 Claims.

This invention relates to hydraulic pumps or motors and moreparticularly to hydraulic pumps or motors of the kind including aplurality of radially disposed, circumferentially spaced piston andcylinder assemblies. Pumps or motors of this general character are wellknown in the art. I

The main object of this invention is to provide a pump or motor of theclass referred to embodying novel and improved structural features byvirtue of which efliciency of operation is increased and manufacturingand assembling costs decreased as compared to pumps of the prior art.

Another object is to provide in such a pump or motor, an improvedorganization of parts for eilecting relative reciprocation between thepistons and associated cylinders.

Anotherobj'ect is to provide an improved arrangement for transmittingtorque directly from a piston reactance member to a cylinder barrel, orfrom the cylinder barrel to the reactance member independently of thepistons.

Another object is to provide a pump or motor of the class referred tohaving a compact construction and arrangement of parts whereby machinesof a given capacity will occupy less room than machines of the sameclass previously known.

Another object is to provide improvements in the pump or motor disclosedin my fcopending application Serial Number 681,991, filed July 24, 1933.Further objects will become apparent from a reading of the followingdescription, the appended claims and the accompanying drawings, inwhich:

Figure l is a longitudinal sectional view of a pump or motor embodyingthe invention, the section being taken on the line. l-i of Figure 2 andparts of the casing being broken away.

Figure 2 is a transverse sectional view taken on the line 2-2 of Figurel.

Figure 3 is a detail sectional view taken on th line 3-3 of Figure 1.

Figure 4 is a perspective view of a slide block.

Figure 5 is a view similar to Figure 2, but

Figure 9 is an end elevation of the roller element shown in Figure 8.For the purposes .of disclosure the embodiments of the invention shownin the drawings will be described as operating as pumps but it will beunderstood that like other machines of the same general class, they alsoare adapted for operation as hydraulic motors.

' The pump shown in Figures 1 to 4, inclusive, comprises a casing formedby end plates l and 2 provided with flanges, (not shown), or anintervening connecting central casing part. The end plate I is formedwith a bore 3 which receives a pintle t having a snug press fit in thebore 3. The pintle is formed with a tapered part 5 flanked bycylindrical bearing surfaces 6 and l. A cylinder barrel 9 formed with atapered bore I0 and with cylindrical bearing races or surfaces H and I2,is mounted for rotation about the pintle. In the form shown rollerbearings l3 and i l are in-' terposed between the pintle bearingsurfaces 6 and I and the respectively associated cylinder. barrelbearing surfaces H and I2. The cylinder barrel is formed with an oilchamber l6 located at the right hand end of the pintle for containinglubricant for the bearings M. The cylinder barrel is adapted to berotated by means of a shaft extension H which may be connected to anysuitable source of power (not shown).

The cylinder barrel fits snugly over the pintle in order to preventleakage of fluid being pumped under high pressure and it is thereforenecessary that the pintle act to some extent as a bearing for therotatable cylinder barrel. The pintle itself does not provide the mainbearing support for the cylinder barrel as will become apparenthereinafter, but it is desirable that the roller bearings i3--I4 beemployed in order to reduce friction to a minimum. The main bearingsupport for the cylinder barrel is provided by the casing itself. In theform shown the cylinder barrel isformed at each end with seats E8 inwhich are mounted bearing races IQ for ball bearlugs 20 cooperating alsowith races 2| mounted in seats 22 formed in the casing end plates I and2. The bearing assemblies I9, 20 and 2| provide the main support for thecylinder barrel and as stated above thebearings I3 and It are employedmerely to minimize the friction between the pintle and the cylinderbarrel, even though the pintle is not relied upon for carrying anysubstantial load as a bearing.

The cylinder barrel is formed with a plurality of radially disposed,circumferentially spaced cylinders 23 which are adapted to communicatewith the barrel bore ill by means of passages 24. In the plane of thepassages 24 the pintle is formed with ports 25 adapted to communicatesuccessively with the cylinder passages 24 when the cylinder barrel isrotated, the pintle ports 25 being in constant communicaton with pintlepassages 26, leading to the inlet and discharge pump connections.Pistons 21 are mounted for reciprocation in the respective cylinders 23and are operated by means to be described, their reciprocation beingtimed with respect to the successive registering of the associatedcylinder passages 24 with the pintle ports 25 so as to effect valvedintake and discharge of fluid. The timing of the reciprocation of thepistons with respect to the registering of the piston passages 24 withthe pintle ports 25 is well understood in the art and need not beexplained in detail.

In accordance with the present invention novel and improved means areprovided for eifecting reciprocation of the pistons relatively to theirassociated cylinders. In the form shown this is accomplished through theprovision of a novel rotatable thrust-transmitting ring assembly, meansfor transmitting driving torque from the cylinder barrel directly to thethrust ring assembly independently of the pistons and means fortransmitting thrust from the ring assembly to the pistons. The thrustring assembly as shown comprises an outer ring part 28 formed with acylindrical outer surface mounted for rotation by roller bearings 29guided in races 30 formed in the inner cylindrical surface of anon-rotatable ring 3|. The ring 3i may be set in a fixed positioneccentric tothe axis of the pintle if the pump is of the constantdischarge type or, if it is required that the discharge be variable atwill, the ring may be mounted for shifting movement transversely of thepintle axis and may be provided with rods 32 for effecting such shiftingmovements.

The outer ring part 28 is formed with cylindrical inner surfaces 33-33separated by an in-- wardly extending flange 34 located intermediate theend faces of the ring part 28. The surfaces 33 extend continuouslyaround the entire inside of the ring part 28.

Radially outward beyond each cylinder is a pair of thrust blocks 35-.-35having arcuate outer surfaces mating with the surfaces 33 of the meansof cheek plates 33 formed with peripheral flanges 31 through which arepassed screws 38 having threaded connection with the outer ring part 28by means of which the cheek plates are secured firmly to the ring part28. The inner faces of the cheek plates clamp the thrust blocks 35securely against the opposite sides of the flange 34.

The cheek plates, are provided with flanges 39 which extend inwardly(towards the common plane of the piston and cylinder assemblies),

these flanges being formed with bearing surfaces which are spacedradially inward from the associated thrust blocks 35 and which areparallel to the inner or bearing surfaces provided by the thrust blocks,and parallel to the bottoms of the bearing wells 35.

In order to transmit thrust between the thrust ring assembly and thepistons there is provided a plurality of slide blocks generallydesignated 40, one being connected to each piston and to the thrust ringassembly. As shown in Figures 3 and 4 each slide block is of one piececonstructionand comprises side portions 4I4l and end portions 42-42, theslide block as a whole thereby constituting a hollow rectangle. Thepiston associated with each slide block is formed with a flat extension43 which extends between the side portions 4I--4l of the slide block,being connected to the latter by means of a pin 44 passing through theextension 43 and the side portions 4I4l. The reduction of the piston toform the flat extension 43 provides a resultant shoulder 45 which is inengagement with the bottom of the slide block. The arrangement thereforeis such that during rotation of the thrust ring assembly by means to bedescribed later, movement of the slide block outwardly with respect tothe pintle will effect an outward or suction stroke of the connectedpiston through the medium of the connecting pin 44. As will beunderstood, only a relatively small effort or force is required to movethe piston on its suction stroke so that the wear on the pin will benegligible. On the other hand when, during rotation of the thrust ringassembly, the slide block is moved inwardly with respect to the pintle,force for moving the piston inwardly on its discharge stroke will betransmitted directly from the bottom of the slide block to the shoulders45 on the piston. Tremendous effort or force is required to move thepiston inwardly on its high pressure discharge stroke and bytransmitting such force directly from the slide block to the piston I amable to eliminate entirely any wear which otherwise would result inconnections of the conventional type heretofore employed between crossheads or slide blocks and pistons.

In most pumps of the prior art it has been customary to transmit torquefrom the cylinder barrel to the thrust ring by means of the pistonsthemselves. This necessarily produces a compound bending, shearing, andthrust compression stress in the pistons resulting in flexing andvibration of the pistons which, in turn, results in noisy pump operationand premature wear. the pistons and/or cylinders of course results inexcessive hydraulic slip rendering the pump unsuitable for high pressureloads. In order to avoid these undesirable characteristics I have formedthe cylinder barrel with extensions 46, there being two extensionsassociated with each cylinder and piston. As shown most clearly inFigures 2 and 4, the extensions 46 associated with each cylinder andpiston extend up into the opening between the side portions 4l-4i of theassociated slide block, the extensions being formed to have slidingengagement with the portion of thepiston extending between the slideblock side portions 4|.

Preferably, torque is transmitted from these extensions to'the slideblocks through the medium of anti-friction bearings. In the form shownthe end portions 42 of the slide blocks are formed with wells 41-41serving to house roller bearings 4848 which engage the cylinder barrelextensions '46-46. Preferably, the roller bearing elements 48 are ofsmall diameter and are so d'imen sioned that there is an overallclearance between the bearings and the ends of the wells 41,amountaoraaoe ing to about one-fourth of the piston stroke in order toprovide for reciprocating movement of the bearings within the wells.With this arrangement the openings between contiguous bearing elementsand between the end bearing elements and the ends of the wells will beof such size as to maintain a supply of oil drawn in by capillaryattraction and surface tension. By virtue of this arrangement the rollerbearings will roll individually while the entire bearing assemblyreciprocates bodily. The assembly therefore provides the advantages ofroller bearings combined with those of an oil film bearing.

In the form shown in Figures 1 to 4, inclusive, the slide blocks alsoare formed with bottom wells 4949 which receive roller bearings 50engaging the inner bearing surfaces 39 of the cheekplates. Similarroller bearing elements 50 are disposed in the thrust block wells 35.The bearings 50 preferably are so dimensioned as to leave atotal overallclearance between contiguous roller bearings and between the end rollerbearings and the ends of the well amounting to about one-fourth of thepiston stroke, thereby obtaining the advantages set forth above withreference to the bearing assemblies 48. i

In order that the slide blocks 40 may reciprocate with respect to thering assembly with a minimum of friction the cheek plates'are formedwith clearance spaces 5|, the arrangement being such that the slideblocks are connected to the ring assembly only through the medium of theroller bearings 48 and the capillary oil flims therebetween.

. In order to stiffen the thrust ring assembly so as to still furtheravoid vibration, bolts 52 are passed through the right hand cheek plate35 and screwed intothe left hand cheek plate. As shown in Figure 2 thesebolts are disposed between adjacent slide blocks and are positioned on acircle' of a diameter somewhat less than the overall diameter of thethrust ring assembly. The cheek plates are thus joined together on twodiameters so as to provide for an extremely rigid assembly.

It will be observed that because of the arcuate formation of the outersurfaces of the thrust blocks 35 the blocks will be permitted to alignthemselves with respect to the outer faces of the associated slideblocks during assembly and before the cheek plates have. been drawntight against the outer ring part 28. This not only makes for perfectalignment of the parts of the completely assembled thrust ring, butrenders it possible to obtain the desired accurate alignment withreduced machining costs. It will be clear that the inner bearingsurfaces 33 of the outer ring part 28, being cylindrical, may ben'iachined accurately at a cost which is considerably less than would bethe cost of machining flat surfaces in this, part for cooperation withthe slide blocks. If the bearing surfaces to cooperate with the slideblocks were to be machined in the thrust ring proper, then it would benecessary to set faces for cooperating with the outer faces of the slideblocks. In other words, in the construction disclosed herein, theaccuracy of alignment of the b' ring surfaces cooperating with the outerfaces of the slide blocks is provided for. by the self-aligning of thethrust blocks35 during assembly.

In the modification shown in Figures 5 to 9, inclusive, the constructionis similar with the exception that the slide blocks, instead of beingformed in one piece, are built up from .two side platesand connectingroller elements. The modified form of slide block generally designated53 comprises two side plate parts 54 which receive the piston connectingpin M which extends through the flat extension 43 of the associatedpiston. The torque transmitting cylinder extensions 46-46 extend betweenthe side plates 54 and in sliding contact with the fiat pistonextension. The side plates 54 of the slide block 53 are connected bymeans of rollers 55 journaled in the plates 54, there being two rollersat each end spaced from each other. Each roller 55 is formed with anenlarged part 56 which engages the associated cylinder extension. Theserollers serve to transmit torque from the cylinder extensions to theslide blocks and the thrust ring assembly.

The machines disclosed herein embody the invention in practical and theat present preferred forms, but it will be understood that variouschanges may be made in the construction and relative arrangement of theparts without departing from the invention as defined in the claims.

I claim:

1. ma hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly provided with parallel outer and inner bearingsurfaces perpendicular to the axes of the respective piston and cylinderassemblies; and means for transmitting force between said ring assemblyand the reciprocable members of said piston and cylinder assembliescomprising for each piston and cylinder assembly a slide block, rollerbearing elements disposed between said slide block and said bearingsurfaces, means for transmitting driving torque directly between thenon-reciprocable member and said slide block, a pintle connectionbetween the slide block and the relatively reciprocable member fortransmitting force therebetween during movement of the relativelyreciprocable member in one direction, and a separate and independentconnection for transmitting force between said slide block and saidrelatively reciprocable member during movement of the latter in theopposite direction, said last named connection comprising a shoulder onsaid relatively reciprocable member with which the slide block is indirect driving engagement.

2. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly provided with parallel outer and inner bearingsurfaces perpendicular to the axes of the respective piston and cylinderassemblies; and means for transmitting force between said ring assemblyand the reciprocable members of said piston and cylinder assembliescomprising for each piston and cylinder assembly a slide block mountedfor sliding movements between and in engagement with the associatedinner and outer bearing surfaces, roller bearing elements fortransmitting driving torque directly between the nonreciprocable memberand said slide block, a pintle connection between the slide block andthe relatively reciprocable member for transmitting force therebetweenduring movement of the relatively reciprocable member in one direction,and a separate and independent connection for transmitting force betweensaid slide block and said relatively reciprocable member during movementof the latter in the opposite direction, said last named connectioncomprising a shoulder on said relatively reciprocable member with whichthe slide block is in direct driving engagement.

3. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly comprising an outer ring part provided with aninwardly extending flange intermediate its end faces, spaced thrustblocks having arcuate outer surfaces engaging the inner curved surfaceof said outer ring part and abutting on opposite sides of said flange,cheek plates secured to the opposite sides of said outer ring part andclamping said thrust blocks against said flange, there being a thrustblock for each piston and cylinder assembly and each thrust block havingan inner bearing surface substantially perpendicular to the axis of theassociated piston and'cylinder assembly, said cheek plates beingprovided with bearing surfaces radially spaced inwardly from therespective thrust blocks; slide blocks, one mounted between each of therespectively associated thrust blocks and cheek plate bearing surfaces;and connections between the reciprocable elements of said piston andcylinder assemblies and the respectively associated slide blocks.

4. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly comprising an outer ring part provided with aninwardly extending flange intermediate its end faces, spaced thrustblocks having arcuate outer surfaces engaging the inner curved surfaceof said outer ring part and abutting on opposite sides of said flange,cheek plates secured to the opposite sides of said outer ring part andclamping said thrust blocks against said flange, there being a thrustblock for each piston and cylinder assembly and each thrust block havingan inner bearing surface substantially perpendicular to the axis of theassociated piston and cylinder assembly, said cheek plates beingprovided with bearing surfaces radially spaced inwardly from therespective thrust blocks; slide blocks, one mounted between each of therespectively associated thrust blocks and cheek plate bearing surfaces;roller bearings disposed between the inner and outer faces of the slideblocks and the thrust blocks and cheek plate bearing surfacesrespectively; and connections between the reciprocable elements of saidpiston and cylinder assemblies and the respectively associated slideblocks. a

5. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relativelyreciprocable member;a rotatable ring assembly comprising an outer ring part provided with aninwardly extending flange intermediate its end faces, spaced thrustblocks having arcuate outer surfaces engaging the inner curved surfaceof said outer ring part and abutting on opposite sides of said flange,cheek plates secured to the opposite sides of said outer ring part andclamping said thrust blocks against said flange, there being a thrustblock for each piston and cylinder assembly and each thrust block havingan inner bearing surface substantially perpendicular to the axis of theassociated piston and cylinder assembly, said cheek plates beingprovidedwith bearing surfaces radially spaced inwardly from the respectivethrust blocks; slide blocks, one mounted, between each of therespectively associated thrust blocks and cheek plate bearing surfaces;connections between the reciprocable elements of said piston andcylinder assemblies and the respectively associated slide blocks; andmeans for transmitting torque directly between the non-reciprocablemembers of the piston and cylinder assemblies and said ring assemblyindependently of said reciprocable members.

6. In a hydraulic pump or motor the combination of a plurality ofrotatable cylinder and piston assemblies each including a relativelynon-reciprocable member and a relatively reciprocable member; arotatable ring assembly comprising a ring part surrounding said pistonand cylinder assemblies, a flange extending around the inner surface ofsaid ring part, a plurality of thrust blocks positioned to abut theinner surface of said ring part, there being a pair of thrust blocks foreach piston and cylinder assembly and the blocks of each pair beingpositioned respectively on opposite sides of said flange and abuttingthe side faces thereof, and cheek plates removably secured to theopposite sides of said ring part and engaging said thrust blocks andclamping the latter against said flange, said check plates beingprovided with inner bearing surfaces respectively spacedfrom and facingsaid thrust blocks; slide blocks interposed between and being slidablysupported by the thrust blocks and the associated inner bearingsurfaces; and means connecting the slide blocks respectively with therelatively reciprocable elements of the piston and cylinder assemblies.

'7. In a hydraulic pump or motor the combination of a plurality ofrotatable cylinder and piston assemblies each including a relativelynonreciprocable member and a relatively reciprocable member; a'rotatablering assembly comprising a ring part surrounding said, piston andcylinder assemblies, a flange extending around the inner surface of saidring part, a plurality of thrust blocks positioned to abut the innersurface of said ring part, there being a pair of thrust blocks for eachpiston and cylinder assembly and the blocks of each pair beingpositioned respectively on opposite sides of said flange and abuttingthe side faces thereof, and cheek plates removably secured to theopposite sides of said ring part and I engaging said thrust blocks andclamping the latter against said flange, said cheek plates beingprovided with inner bearing surfaces respectively spaced from and facingsaid thrust blocks; slide blocks interposed between and being slidablysupported by the thrust blocks and the associated inner bearingsurfaces; means for transmitting force in one direction between each ofthe relatively reciprocable members and the respectively associatedslide blocks; and other means for transmitting force in the oppositedirection between each of the relatively reciprocable members and therespectively associated slide blocks.

8. In a hydraulic pump or motor the combination of a plurality ofrotatable cylinder and piston assemblies each including a relativelynon-reciprocable member for transmitting force therebe-' rocable memberand a relatively reciprocable member; a rotatable ring assemblycomprising a ring part surrounding said piston and cylinder assemblies,a flange extending around the inner surface of said ring part, aplurality of thrust blocks positioned to abut the inner surface of saidring part, there being a pair of thrust blocks for eachpiston andcylinder assembly and the blocks of each pair being positionedrespectively on opposite sides of said flange and abutting the sidefaces thereof, and cheek plates removably secured to the opposite sidesof said ring part and engaging said thrust blocks and clamping thelatter against said flange, said cheek plates being provided with innerbearing surfaces respectively spaced from and facing said thrust blocks;slide blocks interposed between and being slidably supported by thethrust blocks and the associated inner bearing surfaces; meansconnecting the slide blocks respectively 'with the relativelyreciprocable elements of the piston and cylinder assemblies; and meansfor transmitting driving torque between the relatively non-reciprocableelements and the ring assembly independently of the relativelyreciprocable elements. v 9. In a hydraulic pump or motor the combinationof a plurality of rotatable cylinder and piston assemblies eachincluding a relatively non-reciprocable member and a relativelyreciprocable 3 member; a rotatable ring assembly comprising a ring partsurrounding said piston and cylinder assemblies, a flange extendingaround the inner surface of said ring part, a plurality of thrust blockspositioned to abut the inner surface of i said ring part, there being apair of thrust blocks 'for each piston and cylinder assembly and theblocks of each pair being positioned respectively on opposite sides ofsaid flange and abutting the side faces thereof, andcheek platesremovably 40 secured to the opposite sides of said ring part andengaging said thrust blocks and clamping the latter against said flange,said cheek plates being provided with inner bearing surfacesrespectively spaced from and facing said thrust blocks;

slide blocks interposed between and being slidabiy supported by thethrust blocks and the associated inner bearing surfaces; meansconnecting the slide blocks respectively with the relativelyreciprocable elements of 'the piston and cylinder assemblies; and meansincluding roller bearing elements'for transmitting driving torquebetween the relatively non-reciprocable elements and the ring assemblyindependently of the relatively reciprocable elements.

10. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocablemember and a relatively reciprocable member;a rotatable ring assembly provided with parallel outer and inner bearingsurfaces perpendicular to the axes of the respective piston and cylinderassemblies; and means for transmitting force between said ring assemblyand the reciprocable members of said piston and 5 cylinder assembliescomprising for each piston and cylinder assembly a slide block, rollerbearingelements disposed between said slide block and said bearingsurfaces, means for transmitting driving torque directly between thenon-reciprocable member and said slide block, said ring assembly andslide block being so formed and relatively arranged that force istransmitted between the slide block and ring assembly only through saidroller bearings, a pintle connection between the slide block and therelatively reciptween during movement of the relatively recipe rocablemember in one direction, and a separate and independent connection fortransmitting force between said slide block and, said-relativelyreciprocable member during movement of the latter in the oppositedirection, said last named connection comprising a shoulder on saidrelatively reciprocable member with which the slide block is in directdriving engagement.

11. In a hydraulic pump or motor the combiation of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly comprising an outer ring part surrounding saidpiston and cylinder assemblies and having a cylindrical outer surfaceand a cylindrical inner surface provided with an inwardly extendingflange intermediate the end faces of said ring part, spaced thrustblocks having arcuate outer surfaces engaging the inner curved surfacesof said outer ring part and abutting on opposite sides of said flange,cheek plates secured to the opposite sides of said outer ring part andclamping said thrust blocks against said flange, there being a thrustblock for each piston and cylinder assembly and each thrust block havingan inner bearing surface substantially perpendicular to the axis of theassociated piston and cylinder assembly, said cheek plates beingprovided with bearing surfaces radially spaced inwardly from therespective thrust blocks, said cheek plates extending within andengaging the cylindrical inner face of said outer ring part and havingperipheral flanges abutting against the end faces thereof, screwspassing through said peripheral flangesfor securing said cheek plates tosaid outer ring part, and bolts connecting said cheek plates to eachother and being circumferentially spaced on a circle within andconcentric with the outer ring part; slide blocks, mounted one betweeneach of the respectively associated thrust blocks and cheek platebearing surfaces; connections between the reciprocable elements of saidpiston and cylinder assemblies and the respectively associated slideblocks; and means surrounding the outer ring part of the rotatable ringassembly and supporting the latter for rotary movements.

12. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly provided with parallel outer and inner bearingsurfaces perpendicular to the axes of the respective piston and cylinderassemblies; and means for transmitting force between said ring assemblyand the reciprocable members of said piston and cylinder assembliescomprising for each piston and cylinder assembly 'a slide block mountedfor relative translatory movements between the associated inner andouter bearing surfaces, the face of said block adjacent to one of saidbearing surfaces being formed with a well, a plurality of rollerelements in said well for transmitting'force between said bearingsurface and said slide block, there being a total aggregate clearancebetween said roller elements and the ends of said -.well amounting toabout one-fourth the normal stroke of. the relatively reciprocablemember of the associated piston and cylinder assembly, means fortransmitting driving torque directly between the non-reciprocable memberand said slide'block, a connection between the slide block and therelatively reciprocable member for transmitting force therebetweenduring movement of the relatively reciprocable member in one direction,and a separate and independent connection for transmitting force betweensaid slide block and said relatively reciprocable member during movementof the latter in the opposite direction.

13. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly provided with parallel outer and inner bearingsurfaces perpendicular to the axes of the respective piston and cylinderassemblies; and means for transmitting force between said ring assemblyand the reciprocable members of said piston and cylinder assembliescomprising for each piston and cylinder assembly a slide block mountedfor sliding movements between and in engagement with the associatedinner and outer bearing surfa.ces, means for transmitting driving torquedirectly between the non-reciprocable member and said slide block, theface of said block adjacent ,to said torque-transmitting means beingformed with a well, a plurality of roller elements in said well fortransmitting torque, there being a total aggregate clearance betweensaid elements and the ends of said well amounting to about one-fourththe normal stroke of the relatively reciprocable member of theassociated piston and cylinder assembly, a connection between the slideblock and the relatively reciprocable member for transmitting forcetherebetween during movement of the relatively reciprocable member inone direction, and a separate and independent connection fortransmitting force between said slide block and said, relativelyreciprocable member during movement of the latter in the oppositedirection. I

14. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly provided with parallel outer and inner bearingsurfaces perpendicular to the axes of the respective piston and cylinderassemblies; and means for transmitting force between said ring assemblyand the reciprocable members of said piston and cylinder assembliescomprising for each piston and cylinder assembly a slide block assemblycomprising spaced plate parts mounted for sliding movements between theassociated inner and outer bearing surfaces, means connecting saidspaced plate parts to the relatively reciprocable member of theassociated piston and cylinder assembly, a torque-transmitting part fastwith the relatively non-reciprocable member of the associated piston andcylinder assembly, and a roller bearing member joining thespaced plateparts of said slide block assembly and having rolling contact with saidtorque-transmitting part.

15. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly.

comprising an outer part surrounding said piston and cylinder assembliesin spaced relation thereto; a plurality of slide blocks having inner andouter bearing surfaces; connections between said slide blocks and therespective reciprocable members; a plurality of segmental thrust blocksabutting the inner face of said outer ring part and having bearingconnection with the outer surfaces of said slide blocks, there being apair of such thrust blocks associated with each slide block; means otherthan the slide blocks for spacing the thrust blocks of the respectivepairs from each other; means for clamping the thrust blocks against saidspacing means; and means providing inner bearing surfaces facing therespective thrust blocks and having bearing connection with the innersurfaces of said slide blocks.

16. In a hydraulic pump or motor the combination of a plurality ofrotatable radial piston and cylinder assemblies each including arelatively non-reciprocable member and a relatively reciprocable member;a rotatable ring assembly comprising an outer part surrounding saidpiston and cylinder assemblies in spaced relation thereto; a pluralityof slide blocks; connections between said slide blocks and therespective reciprocable members; a plurality of segmental thrust blocksabutting the inner face of said outer ring part and having bearingconnection with the outer surfaces of said slide blocks, there being apair of such thrust blocks associated with each slide block; means otherthan the slide blocks for spacing the thrust blocks of the respectivepairs from each other; means for clamping the thrust blocks against saidspacing means; and means for transmitting torque directly between saidslide blocks and said non-reciprocable 'members independently of saidreciprocable members.

ELEK K. BENEDEK.

